Mathematics of Computation, Vol. 23, No. 108 (Oct., 1969), pp. 787-812 (26 pages) The mathematical and numerical least squares solution of a general linear system of equations is discussed.

"Even the +, −, =, and x signs we take for granted only came into widespread use in the 17th century. Which means that the earlier algebraists we know of … all had expressed their equations mostly in ...